Fix language detection bit swap in T42 header parsing

Correctly map C12 and C13 control bits to fix misidentification of Swedish/Finnish (010) and German (001).
Also ensures Page model, Renderer, and UI properly propagate and display the detected language.

src/teletext/ui.py

@@ -127,10 +127,22 @@ class MainWindow(QMainWindow):
         
         self.status_label = QLabel("Ready")
         self.status_bar.addWidget(self.status_label)
+        
+        self.language_label = QLabel("Lang: English")
+        self.status_bar.addPermanentWidget(self.language_label)
+
+        self.language_names = ["English", "German", "Swedish/Finnish", "Italian", "French", "Portuguese/Spanish", "Turkish", "Romania"]
 
         # Menus
         self.create_menus()
 
+    def update_language_label(self):
+        idx = self.canvas.subset_idx
+        if 0 <= idx < len(self.language_names):
+            self.language_label.setText(f"Lang: {self.language_names[idx]}")
+        else:
+            self.language_label.setText(f"Lang: Unknown ({idx})")
+
     def set_modified(self, modified: bool):
         self.is_modified = modified
         title = "Teletext Editor"
@@ -222,8 +234,7 @@ class MainWindow(QMainWindow):
         view_menu = menu_bar.addMenu("View")
         
         lang_menu = view_menu.addMenu("Language")
-        langs = ["English", "German", "Swedish/Finnish", "Italian", "French", "Portuguese/Spanish", "Turkish", "Romania"]
-        for i, lang in enumerate(langs):
+        for i, lang in enumerate(self.language_names):
             action = QAction(lang, self)
             action.setData(i)
             action.triggered.connect(self.set_language)
@@ -236,6 +247,7 @@ class MainWindow(QMainWindow):
             self.canvas.subset_idx = idx
             self.canvas.redraw()
             self.canvas.update()
+            self.update_language_label()
 
     def prev_subpage(self):
         count = self.subpage_combo.count()
@@ -516,6 +528,7 @@ class MainWindow(QMainWindow):
         if isinstance(page, Page):
             self.current_page = page
             self.canvas.set_page(page)
+            self.update_language_label()
             self.canvas.setFocus()
 
     def insert_char(self, char_code):